446 ANIMAL NATURE OF DIATOME/E. 



breadth, both of the perfectly linear primary, and the 

 elHptico-elongate secondary surfaces is about 0'008. We 

 shall find a perfect agreement with Klitzing's figure by 

 supposing, as usual, that it represents one half of the 

 indicated amplification of 420 diameters, the Navicute 

 being here 8"5 millim. long. 



I believe that some specimens, also collected at Trieste, 

 by Zanardini, (which are perfectly similar to the preceding 

 in external appearance, but of which the Naviculse are 

 shorter and more slender,) belong to a different species, 

 not described by Kiitzing. In the one, the length is five 

 times the breadth ; in the other it is six times in respect 

 to the secondary surfaces, and more than eleven times in 

 respect to the primary. Length 0"036; breadth of the 

 primary smfaces 0-006, of the secondary, 0-0035 millim. 



Schizonema corniculatuni, Ag., (Micromega.) 



Although I might be supported by Kiitzing in the 

 determination of this species, and though my specimens 

 perfectly agree in external appearance with the figure 

 given by this author, still I cannot but confess some 

 doubts as to the species itself. And, in the first place, 

 Kiitzing attributes a larger size to the Naviculse than to 

 those of the preceding species. He says they are no less 

 than ith of a line, therefore 0-054 milhm., and in con- 

 formity to this he represents them 1 -1 millim., with an 

 amplification one half less than what he assigns tohis figure. 

 On the other hand, I find the greatest length 0-03, and the 

 greatest breadth, whether of the exactly linear primary 

 surfaces, or of the elliptico-elongate secondary, 0'007. 

 The length being rather more than four times the breadth, 

 the form of these Naviculse corresponds with that re- 

 presented by Agardh {Icon. Alg. Euroj). ,ia\:f. 4.) I find 

 that the figure given by Agardh himself does not corres- 

 pond with it in external appearance; the figm^e agrees 

 much better with the preceding species. 



It is true that we can find this form more or less rich 



